Bulletin vol 25 no 2 april 2012

Bulletin of the Australian Meteorological & Oceanographic Society Vol 25, No.2, April 2012 ISSN 1035-6576

Contents Editorial ..........................................................................................................................................................................21 President’s Column ........................................................................................................................................................21 News ..............................................................................................................................................................................22 News from the Centres ..................................................................................................................................................25 Obituary — Professor Frank Sherwood Rowland .......................................................................................................26 Conference report ..........................................................................................................................................................27 Articles ...........................................................................................................................................................................28 Jan D. Zika — The Ocean: A contour-wise view...................................................................................................................28 2011 Australian Climate Summary .......................................................................................................................................31

Meet a Member .............................................................................................................................................................36 Snapshot ........................................................................................................................................................................37 Charts from the Past with Blair Trewin: 26 August 1974 ..............................................................................................38 Calendar .........................................................................................................................................................................40

ISSN 1035-6576 Cover picture: Flooding to the north of Euroa, Victoria on 1 March 2012. The picture on the left was taken 3 hours before the picture on the right and shows how the water deepened around the parked vehicle. These pictures highlight the flooding in Victoria this year. Rainfall has been generally high throughout Australia over the last two years, which is discussed in the Australian Climate Summary on page 31. Images: Darren Hocking.

Unless specifically stated to the contrary, views expressed in the Bulletin are the personal views of the authors, and do not represent the views of the Society or any other organisation or institution to which the author(s) may be affiliated.

Editorial

Greetings and thanks Welcome to the April issue of the Bulletin of the Australian Meteorological and Oceanographic Society (BAMOS). My name is Duncan Ackerley and this is my first contribution as the editor of BAMOS. Before I introduce myself fully I would like to say a huge thank you to Linden Ashcroft, the outgoing editor. The standard she has set as editor of BAMOS has been truly fantastic and I hope to maintain those same standards during my tenure. She has been incredibly supportive and enthusiastic in helping me pull this issue together and I would like to personally, and on behalf of AMOS, wish her all the very best in completing her PhD—we hope to hear from you again in BAMOS in the future!

As this is my first editorial I thought I would give you a quick insight into how I am here as editor of BAMOS. My interest in atmospheric science started from the age of five where my schoolteacher gave me an exercise book to draw and write about any interesting weather phenomena that I might see (in an attempt to keep me out of trouble).

It seemed to work; after this point I was hooked and my interest continued to grow. It eventually led me to completing a BSc in Meteorology at the University of Reading in the United Kingdom (UK) in 2003, followed by a PhD in 2007 (also at Reading) on modelling sulphate aerosol under the tutelage of Eleanor Highwood. I then took a post-doctoral research assistant position at Reading and the UK Met Office on dust modelling until October 2008 when I moved to the National Institute of Water and Atmospheric Research (NIWA) in Wellington, New Zealand. I worked on regional modelling of the past

(Eocene, Last Glacial Maximum and mid-Holocene), present and future New Zealand climate before moving “across the ditch” in June 2011 to take up a position at Monash University. My current work is attempting to understand the causes of increased rainfall in north Western Australia.

While working in New Zealand I became involved with the New Zealand Meteorological Society and I was elected as a member of the committee in 2010. I was brought in to oversee the process to make the society’s journal (Weather and Climate) freely available online in an attempt to make it more visible. In working on the committee and contributing to the society I realised how important such organisations are in communicating news and science locally and globally. Therefore, when the editor role came up for BAMOS I applied for the position so that I could make a positive contribution to the society in communicating both its news and some of the science going on in Australia. Having no editorial experience does make the task a little daunting but I am looking forward to getting to know the members of AMOS and publishing the interesting articles that are sent to me.

So on that fi nal note, please feel free to send me any newsworthy items, conference reports, interesting photographs, science articles and notifications of any events that may interest AMOS members, and I will endeavour to include them in BAMOS.

Duncan Ackerley

President’s Column

An introduction from the new president It is my privilege to take over the reins as President of AMOS. It will be a hard act to follow. Neville Nicholls, in his two years in the position, has led a lot of the very unglamorous work involved in bringing the Society up to a more professional level in the way that it runs, in particular bringing our administrative and accounting procedures up to the level required in an organisation of our size. This may not have been especially visible work but it has been essential for the Society to continue to function as a legal entity. All of us owe him a great deal of thanks for his work in this area, which gives us a lot to build on, and for his work for AMOS more generally.

One of the indicators of the strengthening of AMOS has been the continued growth of our conferences. A few years ago, the turnout at our conferences was struggling to get much into three fi gures. The 2012 conference in Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 21

Sydney was the biggest standalone AMOS conference yet, with about 350 participants (see the conference report on page 27), and we are hoping that the 2013 conference in Melbourne will be bigger still. Jason Evans and his team deserve a great deal of credit for bringing us a successful conference at the start of February, which will give next year’s team something to live up to.

While our conference participation has been growing steadily over recent years, our membership has remained fairly stable over the last decade, at about 500. A priority for AMOS in the current year is to try to increase our membership, and a sub-committee led by Michael Hewson of the Brisbane Centre will be looking at ways to make that happen. In particular, our membership is currently very weak amongst operational meteorologists. We also hope to strengthen the new category of Professional

Member, and to increase the role of the category of Fellow in recognising the most distinguished members of the profession in Australia. Strengthening the organisation in Tasmania, where we have a reasonable membership but no currently active Regional Centre, will also be important.

As the fi rst Bureau of Meteorology-based President in a couple of decades, addressing the shortfall of membership in operational areas will be a major focus. There are a number of areas in which there has long been a close partnership between the Bureau and AMOS – not least that the Bureau provides us with office–space, as well as our involvement in the Australian Meteorological and

Oceanographic Journal, and the Weather Calendar. There may well be further partnership opportunities coming up this year—watch this space…

I plan to get to most of the Regional Centres this year, and hope to catch up with as many of you as possible.

We have a strong community in the atmospheric and oceanographic sciences in Australia covering a very diverse range of interests, and we hope that AMOS as a professional society will be able to encompass that range.

Blair Trewin

News

State of the Climate 2012 released Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Bureau of Meteorology (BoM) Media Release

“Australia’s land and oceans have continued to warm in response to rising CO2 emissions from the burning of fossil fuels.”

This is the headline fi nding in the State of the Climate 2012, an updated summary of Australia’s long term climate trends released by CSIRO and the Bureau of Meteorology (14 March 2012).

CSIRO Chief Executive, Dr Megan Clark, said the latest analysis painted a clear decade-to-decade picture of Australia’s climate, while at the same time noting its highly variable nature from one year to the next.

“Much of Australia may have lurched from drought to floods since the previous State of the Climate, but this has occurred against a backdrop of steadily increasing air and ocean temperatures and rising sea levels. What’s more, the rate of change is increasing.”

“The fundamental physical and chemical processes leading to climate change are well understood, and CSIRO and the Bureau of Meteorology observations demonstrate that change is occurring now,” said Dr Clark.

Bureau of Meteorology Acting Director, Dr Rob Vertessy, said this updated summary was based on improved understanding drawn from detailed analysis of our national climate record, which goes back more than a hundred years.

“Ground, ocean and satellite based observations are giving us highly consistent observations of this warming trend.

State of the Climate 2012 confirms that each decade has been warmer than the previous decade since the 1950s, with an increase in the number of warm nights, and more monthly maximum temperature records being broken.”

“CSIRO and the Bureau of Meteorology will continue to provide observations, projections, research, and analysis so that Australia’s responses to the challenges of a changing Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 22

climate are underpinned by robust scientific evidence of the highest quality,” said Dr Vertessy.

State of the Climate 2012 showed a general trend toward increased spring and summer monsoonal rainfall across Australia’s north, and a decline in late autumn and winter rainfall across southern Australia.

Sea levels had risen around Australia at rates equal to or greater than the global average, and sea surface temperatures in the region had increased faster than the global average.

State of the Climate 2012 documents the annual growth in global fossil-fuel CO2 emissions and other greenhouse gases. The CO2 concentration of the atmosphere had risen to around 390 parts per million in 2011, a level unprecedented in the past 800,000 years. During the past decade it has risen at more than 3% per year, which is projected to cause significant further global warming.

The State of the Climate 2012 report can be viewed at: www.csiro.au/State-of-the-Climate-2012

John Church elected a Fellow of the Australian Academy of Science Craig Macaulay

Commonwealth Scientific and Industrial Research Organisation Commonwealth Scientific and Industrial Research Organisation (CSIRO) oceanographer and AMOS Fellow Dr John Church has been elected a Fellow of the Australian Academy of Science (AAS)—one of the highest honours for individual contributions to science awarded in Australia.

Dr Church’s election as a Fellow was announced in Canberra on March 26 and recognises his 34-year career in oceanography, specialising in climate and ocean processes, and sea level rise.

Dr Church is a pre-eminent authority on the rate of 20th century sea-level rise. He is based in Hobart and a CSIRO Fellow (Chief Research Scientist) at CSIRO’s Division of Marine and Atmospheric Research.

The AAS stated in its citation that Dr Church “provided substantial improvements in estimates of ocean heat uptake, resolving discrepancies between observations and models and the long-standing conundrum about the causes of 20th century sea level rise. Church elucidated the dynamical balances at work in some of the major current systems surrounding Australia. His multi-disciplinary work remains a model for the application of oceanographic information to biological fisheries issues”.

CSIRO Marine and Atmospheric Research Chief, Dr Bruce Mapstone, said of Dr Church’s election: “His oversight of international climate research programs, contributions to the evolution of ocean observations, specialist knowledge of polar oceans, and leadership in understanding the forces driving sea level rise easily justify such recognition.

John has fostered development of a specialist sea level research team and his support of young scientists in the Division and in other Australian institutions has contributed to a foundation that will ensure continuing skill in understanding sea level science and what it will mean for nations faced with the challenges of responding to changing climate.”

Dr Church has had three substantial international appointments: t

He has been a member and co-Chair of the Scientific Steering group for the World Ocean Circulation Experiment, designed as a 10-year snapshot of the world’s oceans (1989–1998);

t

He was a member of the international Climate Variability (CLIVAR) research program steering committee (1994–1998); and

t

He was a member and vice-Chair and Chair of the Joint Scientific Committee of the World Climate Research Programme (1999–2008).

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 23

John has been principal investigator for the NASA-French Space Agency TOPEX-Poseidon and Jason satellite altimeter missions, positions he still holds because of their relevance to his sea level rise research.

Dr Church was co-convening Lead Author for the Chapter on Sea Level in the IPCC Th ird Assessment Report completed in 2001, and since 2005 has been a member of the International Oceanographic Commission Scientific Advisory Committee.

He was lead editor of Understanding Sea-level Rise and Variability, a comprehensive overview of current knowledge on the science of sea level rise published in December 2010.

The 420-page book is the work of more than 90 scientists from 13 nations, led by Dr Church, Dr Philip Woodworth from the Proudman Oceanographic Laboratory UK, Dr Thorkild Aarup from the Intergovernmental Oceanographic Commission (IOC), and Dr Stan Wilson from the US National Oceanic and Atmospheric Administration.

Dr John Church. Image: CSIRO.

Andy Hogg wins Australian Academy of Science award AMOS member Dr Andy Hogg has received the 2012 Australian Academy of Science (AAS) Frederick White prize for physical, terrestrial and planetary sciences work, which contributes to the understanding of natural phenomena.

The Frederick White prize is given biennially to scientists under 40 years of age who, according to the AAS, are “engaged in research of intrinsic scientific merit which has an actual or potential contribution to community interests, to rural or industrial progress or to the understanding of natural phenomena.” Dr Hogg is a Fellow at the Research School of Earth Sciences at the Australian National University.

Dr Hogg’s primary area of research focus is centred on the physical processes that govern the ocean and climate, which includes work on ocean eddies, ocean straits, glacial climates and shear instability. The AAS states that Dr Hogg, “has discovered new ways in which the ocean can generate low frequency climate variability, and has applied this knowledge to the prediction of the ocean’s response to climate change. He has demonstrated the importance of resolving small-scale circulation features, particularly in the Southern Ocean region, pointing the way forward for the next generation of climate models.”

Dr Hogg completed his BSc in 1996 from the Australian National University and acquired his PhD in 2002 from the Unversity of Western Australia. After working in Southampton (United Kingdom) at the National Oceanographic Centre, he returned to the Australian National University in 2004.

Dr Hogg has over 30 accepted peer-reviewed publications.

The award will be presented to Dr Hogg at the “Science at the Shine Dome” meeting in Canberra on 3 May. Further information: www.science.org.au/

Frederick White Prize 2012 winner, Dr Andy Hogg. Image: Andy Hogg.

Rabi Rivett, winner of the Christopher Taylor Award 2011 Mark Williams

Chair, AMOS Awards Committee The 2011 Christopher Taylor Award has been awarded to Rabi Rivett, a forecaster from the Bureau of Meteorology, Western Australia Regional Office. The award is for contributions by meteorologists to all kinds of operational forecasting and support activities.

Throughout his career Rabi Rivett has developed varied and extensive innovative inputs into the forecast process through the development of a large number of tools that have significantly improved the operations of the Perth Regional Forecast Centre. These tools include visualisation routines as well as applications that assist in the efficient and effective provision of forecasts. Many of these are web based applications which include a “Combo Viewer” for packaging and summarising the output from Numerical Weather Prediction systems, and a “Microwave Viewer” which is used for viewing microwave imagery in the vicinity of tropical cyclones.

He has also developed a number of other tools and processes, which assist forecasters. These include significant improvements to fog forecasting for Perth Airport, which are so important for the national and international aviation industry. Rabi has been active in developing tools that have improved both the efficiency and effectiveness of the critical fire weather services that are provided by the Western Australia Regional Office. As Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 24

part of this he also developed routines to produce charts of the Drought Indicators for use by the Fire Agencies in Western Australia.

Rabi is recognised as one of the Bureau’s leading developers of “smart tools” which will greatly assist forecasters as they move across to the Bureau’s new Graphical Forecast Editor which is being rolled out across the Bureau.

All of this work has largely been achieved whilst he has been an operational forecaster. Rabi’s work has greatly contributed to the operational work of forecasters, particularly in the Western Australia Regional Office and is a most worthy winner of the Christopher Taylor Award for 2011.

Bureau of Meteorology Regional Director for Western Australia Mike Bergin presenting the Christopher Taylor Award to Rabi. Image: Neil Bennett

News from the Centres

Melbourne Centre news Luke Hande and Nicholas Tyrrell

Regional Sub-editors, Melbourne On the evening of Monday 19 March the State Library of Victoria was host to some of the highest regarded climate change experts in the country. The occasion was to preview the upcoming Intergovernmental Panel on Climate Change (IPCC) Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation, or SREX. The evening featured presentations from three contributing authors; Professor Neville Nicholls (Monash University), Professor John Handmer (RMIT University) and Dr Padma Narsey Lal (CSIRO), with a question and answer session from the approximately 130 attendees.

John Thwaites, Chair of Monash Sustainability Institute and MC for the evening spoke about the diversity of the issues addressed by SREX. The report, two years in the making and involving over 220 expert authors assessing thousands of papers, aims to assess the current state of knowledge regarding weather extremes, and their impact on societies and biosystems.

Professor Neville Nicholls is the co-ordinating lead author of Chapter 3 of SREX: Changes in Climate Extremes and their Impacts on the Natural Physical Environment. He began by providing context of the projected increased occurrence of different weather extremes. He highlighted the difficulty in quantifying the likelihood of extremes such as droughts and fl oods into the late 21st century.

Professor Nicholls stimulated interesting discussion with the audience about the challenges of using climate models to project increases in extremes.

Professor John Handmer, co-ordinating lead author of Chapter 4: Changes in Impacts of Climate Extremes: Human Systems and Ecosystems, indicated that exposure and vulnerability of any group are key determinants of the risk and impacts of climate extremes. He made the point that extreme events will have a higher impact on sectors with closer links to climate such as water, agriculture,

small islands, coastal areas and small economies. Professor Handmer also discussed the challenges of the rigorous IPCC criteria, and the need for multiple lines of evidence for the key statements.

Finally Dr Padma Narsey Lal, co-ordinating lead author of Chapter 6: National Systems for Managing the Risks from Climate Extremes and Disasters, spoke about national systems for managing the risks of disasters. Dr Lal highlighted that disaster risk management and climate change adaptation can significantly influence the extent to which extremes translate into impacts on society, and the importance of “No Regret” mitigation actions that will benefit societies regardless of the severity of changes to the natural environment.

The panel discussion session that followed provided a forum for open discussion between the panel members and the attendees. At the end of the night, the winner surely was SCIENCE! The report is available online at ipcc-wg2.gov/SREX/.

The panel discussion session. From left to right: Professor Neville Nicholls, Professor John Handmer, Dr Padma Narsey Lal and Professor John Thwaites.

Image: Nicholas Tyrrell.

NSW Centre news Fiona Johnson

Vice Chair and Publicity, NSW Centre After a great start to the year with the AMOS 2012 Conference being held in Sydney, the NSW AMOS committee has been busy planning the program of technical talks for the year. We were pleased to help promote and attend the Green Screen Climate Fix Flicks competition as part of the Australian Film Festival which was held at the Randwick Ritz on Tuesday 13 March. The funny and inspirational films made for a fun night—see the full write up in the next issue of BAMOS.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 25

Remember to check the NSW Centre corner of the AMOS website for upcoming talks and events. If you have any suggestions for talks or speakers then get in touch with one of your friendly NSW committee members. Our details are also on the website.

Brisbane Centre news Michael Hewson

Secretary, Brisbane Regional Centre On 1 March eleven of us got together for the AMOS Brisbane Regional Centre Annual General Meeting during a quick lunchtime meeting at the Bureau’s offices in the city.

Prof Hamish McGowan is chairing the committee again this year; the undersigned is your secretary and other committee members are Vikash Prasad, Andrew Wiebe and Michael Gray. Based on the quick “brainstorming” and further discussion at that meeting (as well as the results of the survey Brisbane Centre members participated in last year) the committee will get into planning two professional gatherings in 2012. One gathering will be a professional update and networking meeting—and it is likely to be held in conjunction with the Brisbane chapter

of Clean Air Society of Australia and New Zealand. More soon on that one.

A second meeting will be an expert panel forum on a topic with synergy across AMOS disciplines as well as catering for a regional centre social dimension as well.

We have to recognise the diversity of our membership in terms of distance, discipline and employing organisation— and these (paradoxically) are the reasons why it’s good to meet! Of the 500 plus members of AMOS in 2012, 35 (or so) are in Queensland.

Obituary

Professor Frank Sherwood Rowland 28 June 1927–10 March 2012 Professor Frank Sherwood Rowland, one of the pioneers in understanding how chlorofluorocarbons (CFCs) are responsible for stratospheric ozone depletion, passed away on 10 March 2012 aged 84 after a short illness.

Professor Rowland was born in Delaware, Ohio, United States of America on 28 June 1927 and was the second of three sons. His father was Professor of Mathematics and Chairman of the Mathematics Department at the Ohio Wesleyan University, which provided an academic influence from a young age. He graduated from the Ohio Wesleyan University with a B.A. in 1948. Professor Rowland completed his PhD on the chemical state of cyclotron-produced bromine atoms in 1952 at the University of Chicago (under the mentorship of Professor Willard F. Libby).

Professor Rowland went on to hold academic posts at Princeton University (1952–1956) and the University of Kansas (1956–1964) before becoming Professor of Chemistry at the University of California, Irvine, in 1964. It was at the University of California that Professor Rowland would produce the defining paper on the destruction of stratospheric ozone by CFCs with Mario J. Molina. The paper (published in Nature in June 1974) outlined that chlorine atoms produced by the photodissociation of CFC molecules led to the rapid depletion of stratospheric ozone (and this was before the Antarctic ozone hole had even been discovered!). Such important work led to the United States of America banning CFC-based aerosols in 1978 and ultimately (after the discovery of the Antarctic

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 26

ozone hole) to the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987.

Professor Rowland won many awards for his work including the Nobel Prize in Chemistry along with Mario J. Molina and Paul Crutzen in 1995. He was also elected to the National Academy of Sciences in 1978 and became president of the American Association of the Advancement of Science in 1993.

Professor Rowland’s work on atmospheric chemistry and, in particular, stratospheric ozone destruction by CFCs has been one of the most important contributions to understanding the influence of anthropogenic activity on the Earth’s atmosphere, a contribution that led to one of the most important global treaties aimed at preserving our environment. Professor Rowland is survived by his wife (Joan) along with a son and daughter.

Professor Frank Sherwood Rowland. Image: Markus Pössel, used under Creative Commons Attribution Share-Alike Unported License 3.0.

Conference report

AMOS Annual Conference 2012: Connections in the Climate System 31 January–3 February 2012, Sydney Andrew King1,2, Jason Evans1, Ian Macadam1 and Steven Phipps1.

Climate Change Research Centre, University of New South Wales Australian Research Council Centre of Excellence for Climate System Science.

1 2

During a very wet four days in Sydney (typical of this year’s summer weather in the city) 335 delegates gathered for the AMOS National Conference 2012 at the University of New South Wales (UNSW). The conference was held in the modern John Niland Scientia Building in the centre of the UNSW Kensington campus.

Professionals, students and enthusiasts with an interest in the atmosphere, ocean and climate came from across Australia and further afield to attend, making it the largest national AMOS conference yet. There were seven plenary talks, 172 oral presentations and 146 poster presentations over the course of three and a half days. The plenary talks at the start of each day were well attended and covered a variety of topics; these included palaeoclimate and remote sensing. The Uwe Radok award winner, Jan Zika, discussed his PhD work on a different perspective on ocean circulation (see a summary of this work on page 28). Lisa Alexander, winner of the 2011 Priestley Medal, spoke about the analysis of global temperature and precipitation extremes. Four of the plenary talks were delivered by scientists based outside of Australia, showing the progress that AMOS is making in attracting internationally renowned scientists to its conferences. As well as the plenaries, there were three parallel streams of presentations.

There were three general and 15 special sessions for delegates to attend, including sessions on fi re weather, renewable energy and the hydroclimate of the Murray Darling Basin. These talks showed the breadth of work being undertaken in the Australian meteorological and oceanographic community. Poster sessions provided further opportunities for delegates to present their work and discuss it with their peers. Many stimulating discussions occurred during the morning and afternoon tea breaks and the conference ice-breaker event.

The conference dinner was held on the second night of the conference at Luna Park. With stunning views of Sydney Harbour, the Sydney Harbour Bridge and the Sydney Opera House, the Crystal Ballroom at Luna Park provided an excellent setting. The rain obligingly held off for several hours, allowing pre-dinner drinks to be enjoyed outside next to the harbour. Many people took the opportunity to ride the famous ferris wheel before a delicious three course meal was served. Australian icon H. G. Nelson provided the entertainment with a fast-paced talk on his views on the climate change issue and his work as a presenter of the “Steaming Toad”.

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There was a student get-together on the third night of the conference. A BBQ had been the original plan but due to wet weather an indoor pizza and beer event was held instead. The students got to hear some light-hearted words of wisdom from outgoing and incoming AMOS Presidents Neville Nicholls and Blair Trewin and had the opportunity to get to know other students working in different parts of Australia.

On the same evening, the fi rst AMOS Fellows dinner was held. The dinner was both a recognition of the contribution the Fellows have made to the Society and the science, and an informal chance to socialise and consider future directions for the Society.

A large number of the talks and posters at the conference were delivered by students and judges had the hard task of choosing the winners of the two student prizes. Adele Morrison from the Australian National University was awarded the prize for best student oral presentation for her talk on “Interplay between the zonal momentum balance and overturning in the Southern Ocean”. The prize for best student poster presentation was awarded to Felicity Graham from the University of Tasmania for her poster titled “Application of the ENSO Unified Oscillator theory to an ocean-only model”.

The convenor, Jason Evans, the conference program and local organising committees and a cohort of student volunteers put in a great deal of effort to make the conference a successful one. Our thanks go to Jason and his team as well as the sponsors—the Australian Research Council Centre of Excellence for Climate System Science, the Bureau of Meteorology, the New South Wales Office of Environment and Heritage, the Murray Darling Basin Authority and CSIRO.

Outgoing President Neville Nicholls and H.G. Nelson at the conference dinner. Image: Belinda Campbell.

Articles

The Ocean: A contour-wise view Jan D. Zika

School of Ocean and Earth Science, National Oceanography Centre, Southampton, SO14 3ZH, UK Winner of the 2010 Uwe Radok award for the best PhD Thesis 2010.

Address for correspondence: J.D.Zika@soton.ac.uk

1. Introduction Satellite images of atmospheric cloud cover and ocean colour reveal a rich tapestry of turbulent processes covering the globe. It has long been established that these turbulent processes are critical to the heat engine of the atmosphere (Andrews and McIntyre 1976). Solar radiation causes upward and downward motions at the equator and downward motion towards the poles. Atmospheric flows are, on average, zonal. Hence it is turbulent fluxes (due to the weather systems we see in satellite images) which link the rising warm air and sinking cold air (Karoly et al.

1997).

The natural way to conceptualise the atmosphere is in latitude-isotherm space. With thermally driven diapycnal (across equal-density surfaces) fl ows in the vertical axis and turbulent fluxes in the horizontal axis, aside from some asymmetries such as the Walker Cell, the dominant circulation of the atmosphere is zonally symmetric.

buoyancy fluxes and mechanical mixing. These fluxes vary remarkably from ocean to ocean and sea to sea.

There is no coordinate system which yet captures all of the important features of the overturning of the ocean.

Zonally averaged treatments are common but each ocean basin must be treated separately. Descriptions of the Southern Ocean have been overcome through approaches taken from the atmospheric literature; however, there is no solution for the low latitude marginal seas such as the Mediterranean and Red seas whose flows are largely eastwest.

In the recent PhD thesis of Jan D. Zika (Quantifying Ocean Mixing from Hydrographic Data, University of New South Wales, 2010), a new framework is described, the tracer-contour framework. Th is article introduces that framework.

2. The tracer-contour framework

A major difference between the ocean and atmosphere is that the ocean has continental barriers. The ocean’s continental boundaries block the zonal fl ows of the type seen in the atmosphere (bar a narrow stretch of the Southern Ocean). Continents allow significant poleward flows of heat without the need for eddy fluxes. Continents separate oceans and marginal seas.

Let us begin by imagining a water parcel in the ocean. If this water parcel moves without changing its temperature and salinity then it must follow a path of constant temperature and salinity, a tracer-contour. If it follows such a path, the water parcel does not mix with its surroundings or contribute to large-scale budgets of heat and salt in the ocean.

In addition, the ocean is not a heat engine, but a mechanically controlled thermohaline circulation.

Diapycnal fl ows are driven by both thermal and haline

In order for the water parcel to change its temperature and salinity there must either be a flux of heat or salt or the water parcel must mix with its surroundings. Thus, any flow across a contour of constant temperature and salinity must be accompanied by mixing or sources and sinks.

Figure 1: Schematic showing contours of constant tracer forming a natural coordinate for understanding the Southern Ocean Overturning Circulation.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 28

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Figure 2: Contributions to layer cross-contour transport from the isopycnal mixing term (black bars) and the vertical mixing terms (white bars) across the southern (a), central (b) and the northern contours (c) of the Antarctic Circumpolar Current.

We are primarily interested in the ocean’s role in the climate system and the way in which it transports heat and salt and contributes to global balances of these properties.

Hence we are primarily interested in the component of the ocean circulation which crosses contours of constant temperature and salinity. It is in this reference frame that the overturning circulation of the ocean is best understood.

Two contrasting scales of advection occur in the ocean, isopycnal (along equal-density surfaces) and diapycnal.

That is, diabatic fl ow across isopycnals and adiabatic flow along isopycnal surfaces. Thus there are three possibilities for our water parcel: adiabatic flow along the tracer-contour (u||), quasi-adiabatic flow along isopycnals but across tracer contours (u‐) and diabatic fl ow across isopycnals (wγ). Flow which does not change its temperature and salinity (u||), does not change its density and is truly adiabatic. Flow that does not change its temperature and salinity (u||), does not change its density and is truly adiabatic.

A water parcel can change its temperature and salinity without changing its density hence fl ow can be across a tracer-contour on an isopycnal (u‐). It can do this either by mixing along isopycnals or mixing diapycnally with compensating effects due to temperature and salinity.

Hence the advection along an isopycnal and across a tracer-contour can be related to rates of along isopycnal mixing and vertical mixing.

For a water parcel to change its density, it must mix diapycnally. Diapycnal flow (wγ) can thus be related to the rate of diapycnal mixing and the distribution of density.

The tracer-contour-wise averaged ocean circulation depends on both the quasi-adiabatic cross tracer-contour flow (u‐) and the diabatic diapycnal flow (wγ).

Just as turbulent processes close the zonally averaged circulation of the atmosphere, they are fundamental to the contour-wise averaged ocean circulation. In the following, this framework leads us to a deeper understanding of the

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 29

balance of diapycnal and isopycnal mixing in specific components of the overturning circulation.

3. Tracer-contours and the Thermohaline Overturning Circulation Perhaps the ocean’s clearest example of flow across tracercontours is the outflow of warm salty water from the Mediterranean Sea. A zonally averaged view is useless here as Mediterranean water fl ows east to west through the Strait of Gibraltar and spreads into the Atlantic.

Integrating along contours of constant temperature and salinity on isopycnals, Zika and McDougall (2008) establish the balance of lateral and vertical mixing in the outflow.

In the Southern Ocean, warm salty water of northern origin upwells along sloping isopycnals, providing a connection between the deep ocean and the atmosphere (Figure 1). Closed temperature contours exist at large depth ranges of the Southern Ocean. Zika et al. (2009) exploit this and determine the relationship between the Southern Ocean Overturning Circulation and isopycnal and diapycnal mixing (Figure 2).

The studies discussed above have exploited specific geometries of the Mediterranean Outflow and the Southern Ocean, but can we use the tracer-contour framework to quantify ocean circulation and mixing everywhere?

4. The tracer-contour inverse method Methods for quantifying ocean circulation from observations, inverse methods, have proven useful in determining the mean circulation of the ocean. However, robust estimates of the diapycnal and Southern Ocean components of the overturning circulation have proven difficult as has determining the mixing rates intimately linked to that overturning.

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Figure 4: An estimate of the vertical profile of the isopycnal mixing coefficient for tracers and a comparisons with other lateral mixing estimates in the same region.

Killworth 1986), Zika et al. (2010a) develop the tracercontour inverse method. The method considers fl ow across tracer-contours (temperature, salinity or any other tracer) on isopycnals, conserves tracers on isopycnal layers and relates geostrophic flow in the vertical via the thermal wind equation.

Karoly D.J., McIntosh, P.C., Berrisford, P., McDougall, T.J. and Hirst, A.C., 1997. Similarities of the deacon cell in the Southern Ocean and Ferrel cells in the atmosphere.

Quarterly Journal of the Royal Meteorological Society, 123, 519–526.

Within the tracer-contour framework, existing inverse methods can be reproduced. The method exploits both the natural coordinate system of the ocean (tracer-contours) with the natural observational coordinate (transcontinental sections). The result is a method in which the ocean circulation and rates of isopycnal and diapycnal mixing are robustly estimated.

The tracer-contour inverse method has been validated and used to estimate, perhaps for the fi rst time, the vertical structure of the isopycnal mixing coefficient for tracers (Zika et al. 2010b; Figures 3 and 4).

Killworth, P., 1986. A Bernoulli inverse method for determining the ocean circulation. Journal Physical Oceanography, 16, 2031–2051.

Wunsch, C., 1978. The North Atlantic general circulation west of 50°W determined by inverse methods. Reviews of Geophysical and Space Physics, 16 (4), 583–620.

Zika, J.D. and McDougall, T.J., 2008. Vertical and lateral mixing processes deduced from the Mediterranean water signature in the North Atlantic. Journal of Physical Oceanography, 38, 164-176.

5. Going global with tracer-contours

Zika, J.D., Sloyan, B.M., and McDougall, T.J., 2009.

Diagnosing the Southern Ocean overturning from tracer fields. Journal of Physical Oceanography, 39, 2926–2940.

Major avenues of research have been opened by Zika’s PhD thesis. One is to apply the tracer-contour inverse method globally and robustly determine the Thermohaline Overturning Circulation and global rates of mixing.

Zika, J.D., McDougall, T.J., and Sloyan, B.M., 2010a. A Tracer-contour inverse method for estimating ocean circulation and mixing. Journal of Physical Oceanography, 40, 26–47.

In his present role, Zika is using state of the art numerical ocean models and hopes to develop methods for their contour-wise interpretation.

Zika, J.D., McDougall, T.J., and Sloyan, B.M., 2010b. Weak mixing in the eastern North Atlantic: An application of the tracer-contour inverse method. Journal of Physical Oceanography, 40, 1881-1893.

References Andrews, D.G. and McIntyre, M.E., 1976. Planetary waves in horizontal and vertical shear: The generalized Eliassen– Palm relation and the mean zonal acceleration. Journal of the Atmospheric Sciences, 33, 2031–2048.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 30

2011 Australian Climate Summary National Climate Centre, Bureau of Meteorology 1. Overview 2011 was another wet year for Australia, with data collected by the Bureau of Meteorology showing that the Australian mean rainfall total for 2011 was 705 mm (240 mm above the long-term average of 465 mm), placing the year at the second-wettest since comparable records began in 1900.

Back-to-back La Niña events led to a two-year rainfall total of 1408 mm, which is the highest total on record behind 1407 mm in 1973–74.

The 2010–11 La Niña, one of the strongest on record, continued to dominate climate patterns during the fi rst part of 2011 before decaying in autumn. A second La Niña developed in spring 2011 and, although weaker than the fi rst event, was associated with rainfall significantly above average across much of the country. It is likely that a record warm eastern Indian Ocean also contributed to above average rainfall in 2011.

From January to March, rainfall was generally very much above average in most areas, and April was rather wet over the north of Western Australia and the Northern Territory. Falls greater than 300 mm across much of the tropical north led to the wettest March on record for Australia as a whole, with average rainfall of 149 mm topping the previous 1989 record by 23 mm. The period from May to September (when La Niña had receded) saw rainfall below average for most of the country. October was very wet in the western half of the country, with Western Australia experiencing its third-wettest October on record. November rainfall was above average for most of the country, while December was wet for the southwest and parts of Queensland. For the year as a whole, the majority of Australia received above-average rainfall; the only regions with below average rain were patches

of southwest Western Australia, western Tasmania and pockets of New South Wales and south-east Queensland.

The Australian area-averaged mean temperature in 2011 was 0.14°C below the 1961 to 1990 average of 21.81°C. This was the fi rst time since 2001 (also a wet, La Niña year) that Australia’s mean annual temperature was below the 1961–1990 average. Even though, when taken over the whole country, the mean temperature was below average, the southern half of Australia was warmer than usual.

In 2011, maximum temperatures averaged 0.25°C below normal across the country, while minima averaged 0.03°C below normal. Contrasting this, the global mean temperature in 2011 was the highest for any year that began with a La Niña. Australia was one of the few places on the globe to experience cooler-than-average temperatures in 2011.

Despite the slightly cooler conditions in Australia in 2011, the country’s 10-year average continues to demonstrate the rising trend in temperatures, with 2002–2011 tying for the equal-warmest 10-year period on record for Australia, at 0.52 °C above the long-term average.

2. A tale of two La Niñas - Australia’s second-wettest two-year period on record Rainfall during 2011 was very much above average across most of Australia, with record high falls over the Kimberley, south-eastern and central Western Australia, and across parts of the north of the Northern Territory (Figure 1). The year 2011 was the second-wettest on record for Australia as a whole (Figure 2), the wettest on record for Western Australia, and third-wettest for the Northern Territory and northern Australia as a whole (the area north of 26°S).

Figure 1: 2011 annual rainfall compared against historical rainfall records.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 31

Figure 2: 2011 Annual and decadal mean rainfall (mm) for Australia since 1900. The average for the most recent 10-year period is shown in darker grey.

A very heavy tropical monsoon season was associated with exceptional summer rainfall over most of Australia.

Victoria recorded its wettest January in 112 years of records and its third-wettest February (highest state-wide total since 1973). February was also the second wettest on record for Australia and Western Australia, and the wettest on record for South Australia. March was the wettest on record for Australia as a whole, as well as for the Northern Territory and Queensland, and the third wettest for South Australia.

Even as the La Niña decayed from late April, the Kimberley and the north of the Northern Territory continued to see very much above average rainfall. All states recorded below average May rainfall. June was notable for the lack of rainfall in the south-east—the main rainfall deficiencies observed in 2011 occurred during winter and early spring in the south-east of Australia.

As has occurred several times in the historical record, La Niña conditions redeveloped during spring and continued beyond the end of 2011. Although it was significantly weaker than the 2010–2011 event, it occurred in conjunction with record warm conditions across the eastern Indian Ocean. October was very wet in the western half of the country, while November rainfall was generally above to very much above average in most regions except for coastal Queensland. December rainfall

was very much above average for much of southwest Western Australia, with some inland parts recording the highest falls on record. Above average December rainfall was also recorded over much of Queensland and adjacent areas of the Northern Territory, South Australia and New South Wales.

3. First cooler-than-average year since 2001, courtesy of persistent wet weather. However, equal-warmest 10-year period on record For the fi rst time in a decade, Australia’s annual mean temperature was below the 1961–1990 average (Figure 3).

Daytime maximum temperatures were suppressed over much of the mainland as a result of the heavy rainfall at both the start and end of 2011, and relatively frequent southerly airstreams in the first half of the year.

For the year as a whole, both minimum and maximum temperatures were below to very much below average in the tropics and subtropics. In contrast, mean temperatures were above average for most of southern Australia (Figure 4).

Widespread below average daytime temperatures were notable between February and May, while August maxima were very much above average for most of Australia, excluding the tropics. In November, maximum

Figure 3: Annual and decadal mean temperature anomalies for Australia (compared with the 1961 to 1990 average). The average for the most recent 10-year period is shown in darker grey.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 32

Figure 4: 2011 annual mean temperatures compared against historical temperature records. temperatures were once again well below normal in the north-west of the country. Unusually warm overnight temperatures were a feature in southern Australia in a number of months, including January, July, August, and October. Meanwhile, May and June produced exceptionally low overnight temperatures across northern Australia: in a large area of the Kimberley and the north of the Northern Territory minima were the lowest on record.

2011 was clearly the warmest year on record for southwest Western Australia including Perth, with mean temperatures for the region 1.16°C above the 1961 to 1990 average, and 0.41°C above the previous record, set in 1999.

Averaged over Australia, autumn mean temperatures were 1.15°C below the historical average, the coolest since comparable records began in 1950. Maximum temperatures were the second coolest on record and minima the fifth coolest. These months were particularly cool across the tropics. Parts of the eastern Kimberley and the Northern Territory (equating to 8.4% of Australia’s total area) experienced their lowest autumn maximum temperatures on record, while the Northern Territory as a whole experienced its coldest autumn on record.

The start to the dry season was the coldest on record over the Northern Territory as a result of persistent low temperatures in the northern tropics from late May to mid-June. The Northern Territory was particularly cool in May, including a Northern Territory record for May of −4.2°C at Arltunga on the 31 May, and a May record of five consecutive nights below 0°C at Alice Springs, between 27 and 31 May. In June, the Northern Territory saw six consecutive days in which the temperature remained below 15°C in at least one location over the region, the longest such streak for any month since 1998. In addition, for the fi rst time ever Darwin’s minimum temperature dropped below 20°C every night during June. This was the fourth-longest run of cool nights in the Northern Territory capital since records began at the airport in 1941.

Southern Australia experienced two notable heat events during 2011. The fi rst was a heatwave lasting from late January to early February across the southern mainland.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 33

Maximum temperature records were set in southeast Western Australia and central South Australia, including an all-time record of 48.1°C at Woomera on 25 January.

Sydney experienced its longest hot spell in 152 years of record with seven consecutive days above 30°C and five nights above 24°C. The second heat event occurred during early August when a high pressure system brought unseasonable early season warmth to south-eastern Australia. Melbourne set an early-season record high overnight temperature of 17.3°C on 4 August and, averaged over the month, it was the warmest August on record for Tasmania.

The highest temperatures for the year occurred in December 2011 affecting the Pilbara region. Multiple sites broke the previous Western Australia December record (48.8°C at Mardie on 26 December 1986) over three consecutive days. Roebourne recorded 49.4°C on 21 December, while Onslow Airport recorded 49.2°C on 22 December and Learmonth recorded 48.9°C on 23 December. Roebourne’s 49.4°C was the highest temperature recorded in Australia since 1998.

4. The influence of La Niña on Australian temperatures In general, widespread cloud cover and rainfall are associated with cooler daytime temperatures for Australia.

For this reason, Australian average temperatures are generally cooler during La Niña years. This is particularly true for years with strong and sustained La Niña conditions, accompanied by high rainfall across large parts of the continent. Eight of the last nine years with sustained La Niña conditions recorded a cooler-thannormal Australian average temperature, with four of those years experiencing very cool conditions (Figure 5).

5. Flooding, storms, and fires The 2010–11 La Niña event directly contributed to numerous and significant floods that continued throughout the summer and into autumn 2011. The period from late November 2010 to mid-January 2011 was extremely wet through much of eastern Australia, with cumulative

Figure 5: Annual mean temperature anomalies for Australia (compared with the 1961 to 1990 average), with La Niña years marked in teal (nine La Niña years in total, including 1989). La Niña years are defined as those where central Pacific sea surface temperature anomalies exceeded −1 °C for a sustained period leading into the start of the year. rainfall resulting in flooding which was amongst the most significant in Australia’s recorded history.

The most notable fl ood events for the year occurred in south-east Queensland and nearby areas of northern New South Wales, where many catchments were already subject to, or recovering from, fl ooding. Around Rockhampton, in the Fitzroy basin, flooding (which began in late 2010) continued into early January. During the second week of January severe river and flash fl ooding affected the Brisbane catchments. Th is also affected nearby towns including Toowoomba and Grantham, resulting in loss of life and extensive property damage. On 13 January Brisbane recorded its second-highest flood level in the last 100 years, after January 1974.

Northern Victoria also experienced notable and damaging flooding following exceptional summer rainfall; initially from mid-January with flash fl ooding in the Grampians and surrounding areas and riverine flooding downstream in the Wimmera and Loddon catchments. February brought renewed flooding to these regions and additional flash fl oods in central Victoria. Some of the riverine flooding in northern and western Victoria was longlived, with flatter parts of the lower catchments inundated for many weeks. There was also significant fl ooding in northern Tasmania and southern inland New South Wales at this time.

Many other floods occurred during the year. A monsoonal burst in mid-March resulted in extensive flooding isolating communities across the Fitzroy, Ord and Pentecost River catchments in the eastern Kimberley, as well as causing prolonged flooding in many catchments through western Queensland and along the tropical coasts. Other notable floods occurred in central Victoria, the south coast of NSW and eastern Tasmania in late March; southeast Victoria, together with northern and eastern Tasmania in mid-April; the NSW coast in mid-June. Major floods also occurred in northern inland New South Wales west of the Great Dividing Range, as well as in inland Queensland, in the latter part of November and early December.

A number of significant tropical cyclones affected northern Australia in 2011. Tropical cyclone Anthony crossed the Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 34

central Queensland coast near Bowen on 30 January as a marginal Category 2 storm, while tropical cyclone Bianca brought rain and strong winds to the Kimberley and Pilbara coast in late January. Tropical cyclone Yasi—the strongest cyclone to make landfall in Queensland since at least 1918 (another La Niña year)—crossed the coast near Mission Beach, between Cairns and Townsville, on 3 February causing extensive damage. The slow-moving tropical cyclone Carlos brought very heavy rainfall to the Top End between 15 and 17 February, breaking numerous records, including the highest daily rainfall at Darwin Airport with 367.6 mm on the 16 February and highest 3-day total at Darwin Airport with 684.8 mm.

Damaging storms were also a feature of the year, with numerous thunderstorms when La Niña conditions were dominant in summer and spring. In addition to the previously mentioned events, severe thunderstorms brought extreme rainfall to parts of Victoria, causing flash flooding around Mildura, the Melbourne metropolitan region and eastern Victoria during 4 February. Daily rainfall totals of 100–200 mm were widespread during the event. Further severe storms with large hail and a tornado affected areas near Melbourne on 25 December with widespread damage to cars and houses.

The very high rainfall during 2010 and 2011 was accompanied by strong vegetation growth across the usually arid inland. This provided ample fuel for grassfires in central Australia in the dry season (winter and spring), with widespread fi res in more remote regions in the south of the Northern Territory and central and western Queensland. Significant fires also occurred in the southwest of Western Australia. In early February fi res burnt out of control near Red Hill, in the Swan Valley, and in the Roleystone and Kelmscott areas over 100 homes were destroyed or partially damaged. Late in the year fires near Margaret River in Western Australia destroyed a number of houses.

6. Sea surface temperatures in the Australian region Sea-surface temperatures (SSTs) in the Australian region were slightly cooler than 2010, but were still 0.39°C above average (Figure 6). The most notable monthly average

Figure 6: Annual and decadal mean sea surface temperature anomalies in the Australian region (compared with the 1961 to 1990 average). The average for the most recent 10-year period is shown in darker grey. anomalies were January, ranking second (+0.39°C), and November, third (+0.43°C), warmest on record.

Furthermore, during 2011, 10 out of 12 months ranked in the top 10 warmest observations on record for their respective months. Conditions were particularly warm in the eastern and southern Indian Ocean with record warm conditions occurring in autumn, winter, and spring to the west of Perth.

SSTs in the tropical Pacific Ocean show the clear pattern of a La Niña event: below average SSTs in the central to eastern Pacific and above average SSTs in the western Pacific region. The La Niña pattern was also apparent below the surface across the tropical Pacific. Sub-surface temperature anomalies in the western Pacific reached a peak of 4°C above the long-term average during February 2011, before later weakening. Temperatures below the surface of the eastern Pacific approached 4 °C below normal through spring 2011.

The past ten years (2002-2011) has seen the warmest 10year averaged SSTs in the Australian region since 1910 (see Figure 6).

7. Globally, 2011 the warmest La Niña year on record Preliminary data released by the World Meteorological Organization (WMO) on 29 November estimated the global mean temperature for 2011 (January-October) at 0.41°C ±0.11°C above the 1961–1990 annual average of 14.0°C. At present, 2011’s nominal value ranks as the

equal-tenth-highest on record, with the 13 warmest years having all occurred in the 15 years since 1997. (Ed.—the final 2011 data, released in March, showed an anomaly of +0.40°C, ranking eleventh) The 10-year global average from 2002–2011 was 0.46 °C above normal, making it the equal-hottest 10-year period on record.

Of the 23 climate regions monitored by the WMO globally, northern Australia was the only region to record coolerthan-normal temperatures during 2011, in association with very heavy rainfall.

Years commencing with a strong La Niña are typically 0.10 to 0.15 °C cooler than the years preceding and following them. Although global temperatures have not been as warm as the record-breaking values seen in 2010, 2011 was the warmest La Niña year on record.

8. Accessing Australia’s climate change datasets The Bureau of Meteorology is responsible for collecting, managing and safeguarding Australia’s climate archive.

Several high-quality datasets have been developed from this archive to identify, monitor and attribute changes in the Australian climate. Extensive rehabilitation work has been undertaken on these data to ensure they have not been compromised by changes in site location, urbanisation, exposure or instrumentation over time.

The high-quality data can be www.bom.gov.au/climate/change/hqsites/

accessed

at:

Weather Tipping Competition “Well - the Bureau always gets the forecasts wrong anyway...how hard can it be?”

Sound familiar? AMOS gives you the chance to put your forecasting skills to the test in our annual Weather Tipping Competition. It works like your office footy tipping competition but instead of winners, we want your predictions of minimum temperature, maximum temperature and rainfall. Locations change week-by-week, are you a better player at home or on the road? Among the players are some new recruits and seasoned campaigners: but can you beat the Bureau?

Entry is free and open to both AMOS members and the general public. The competition will run thoughout the 2012 football season and prizes will be awarded at the end for the best-and-fairest. Join up anytime and see how good at the forecasting game you really are! Happy forecasting!

For more information and to subscribe to this season’s competition visit: tipping.amos.org.au Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 35

Meet a Member

Michael Hewson Where does this find you?

Despite being 49 at the time, I commenced a PhD in mapping science at the School of Geography, Planning and Environmental Management, The University of Queensland, to look at the aerosol effect on clouds for south-east Queensland using remote sensing, weather models and geo-statistics.

What do you do?

I’m trying to make sense of all these acronyms, instruments and processes related to the research project; for example: “WRF-Chem”, “MODIS”, “AERONET,” “CALIPSO”, “CloudSat”, “ceilometer”, “R”, “ArcGIS”, “cokriging”, “lidar/ceilometer,” “rain-radar”, “2nd indirect effect” and “Angstrom exponent”. Isn’t it a pity the National Aeronautics and Space Administration aerosol polarimetry sensor ended up in the ocean last year— would have been great!

Why did you get into it?

Clearly some classes of employment can get just plain boring—and given the hours we spend at raising revenue—it’s worth doing something interesting!

Information systems projects are all the same after the first few—and remembering an earlier stint as an Air Traffic Controller—I thought I’d marry some very basic meteorological observer training from the Bureau of Meteorology people at the Royal Australian Air Force Base East Sale, with a long standing interest in physical geography and a newly acquired expertise in map-making and remote sensing. It was either that or a red sports car.

What is the best thing about what you do?

It’s the combining of interests and skills and looking into something new.

What did you want to be when you were 10?

Ten? Now how long ago was that? There was this embryonic paradoxical mixture of books and the outdoors if I recall it right! Otherwise, clueless.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 36

Michael Hewson—Secretary, Queensland Centre. Image: Will von Dauster How do you relax?

Despite the digital revolution, trudging a large format (4x5 inch) wooden film camera to a place somewhere (anywhere) is my escape of choice—it makes you slow down, think and consider the landscape photograph as a fine art. Peter Dombrovskis (for those that know) was an inspiration—for more reasons than art.

What is your favourite holiday destination?

Anywhere at the end of a road or an aeroplane! My newest “favourite” place, courtesy of a 6-month visit to the National Oceanic and Atmospheric Administration in Boulder Colorado USA, has to be the Rocky Mountain National Park.

Snapshot

Severe thunderstorm Melbourne, 9 November 2011 Hamish Ramsay

This image shows a shelf cloud associated with the gust front of a severe thunderstorm over Melbourne on 9 November 2011. The photograph was taken at approximately 6.30pm, looking southward from Kew/ Fairfield area.

Radar images of the storm can be found at:

This thunderstorm was associated with very heavy rain and golf-ball sized hail, which affected Melbourne’s southeastern suburbs.

If you have an image of the weather near you to share, send it to duncan.ackerley@monash.edu, or post it on the AMOS Facebook page. — Ed.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 37

www.theweatherchaser.com/radar-loop/IDR024-melbour ne/2011-11-09-07/2011-11-09-08

Charts from the Past with Blair Trewin

26 August 1974 1974 was a year which featured numerous major fl oods throughout eastern and central Australia. January, by far the wettest month on record in Australia, saw the most extensive fl ooding, but there were also major fl oods in various parts of the country in March, April and May. There was some respite in mid-year (apart from waters making their way downstream from earlier events), but heavy rain returned to the south-east in August, over catchments which were already very wet.

A trough developed over South Australia on 24 August, with an associated upper-level low. Th is developed into a surface low over northern inland New South Wales on 25 August, before drifting very slowly. Initially it moved south to be centred over the Riverina on 27 August, before then turning east. It fi nally moved off the NSW south coast on 29 August, then accelerated and tracked southeast of Tasmania.

The initial movement of the low produced widespread rain over the eastern interior. Falls were mostly light to moderate although there were some locally heavier totals, including 86 mm at Oakwood (near Augathella) on 25, August and 71 mm at Mt. Manora (near Ivanhoe) on 26 August.

The heaviest totals, however, developed in south-eastern New South Wales from 27 August onwards as a deep easterly flow became established on the southern flank of the low. The most extreme totals were on the eastern edge of the Southern Highlands. Knights Hill, near Robertson, had a two-day total of 656 mm on 27–28 August, including 404 mm on 28 August, and several other sites in the Robertson area had two-day totals exceeding 500 mm.

As the system shifted slightly south, so did the heaviest

rainfalls, with 188 mm at Araluen on 29 August, and 141 mm at Nicholson (Victoria) on 30 August.

It was a particularly notable rain event in the upper Murrumbidgee catchment. Canberra exceeded 40 mm on each of the three days 27–29 August for a three-day total of 136 mm, but falls were much heavier in the Brindabella Ranges, with three-day falls of 350 mm at Bendora Dam and 273 mm at Honeysuckle Creek. With an unusually heavy snowpack below 1500 m from cold outbreaks earlier in the month, and relatively warm temperatures during this event, there was also substantial snowmelt. This all contributed to extremely high flows in the catchment. Unlike the 2012 event, Burrinjuck Dam was already almost full and unable to contribute much to fl ood mitigation. The end result was that, despite relatively modest falls locally (the highest daily total being 18 mm on 27 August), and much less extensive heavy falls generally than in the 2012 event, the Murrumbidgee reached its highest instrumentally recorded flood with a peak of 10.74 m at Wagga Wagga.

There was also moderate to major flooding in several other river systems, including the Lachlan, Shoalhaven, and Hawkesbury/ Nepean. Three deaths were attributed to the floods, two west of Sydney and one near Nowra. Flooding west of the divide made its way slowly downstream over the following months, reinforced by further rain in September and October, and did not finally clear the state until early 1975.

Synoptic chart for 0000 UTC (1000 AEST), 26 August 1974

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 38

Climate science winter school July 9-13, 2012. School of Earth Sciences, Melbourne University

The ARC Centre of Excellence for Climate System Science will host its first annual winter school on July 9-13 at the School of Earth Sciences, The University of Melbourne. This is a high-level education program for honours and graduate students interested in climate science. Most students will have an undergraduate background in maths, physics or computational science.

The winter school will provide a broad overview of the key areas of climate science in the Centre’s main research programs. Researchers will explain how the Centre uses physics, maths, biology and hydrology, coupled with high performance computers to understand the processes and phenomena associated with climate science, climate variability and climate change.

Sessions of the winter school will be dedicated to the key drivers of Australian climate including tropical convection, climate extremes and land surface and ocean processes.

The school will also feature sessions on the modelling and data tools used in the Centre, particularly the ACCESS modelling system and CMIP5 data sets. Centre of Excellence staff based at Universities and partner organizations will deliver lectures.

The school is open to anyone, and funding is available to support attendance. However, priority will be given to honours and graduate students working on climate science problems. The number of places is strictly limited.

To register, email a one page CV and a half page statement on why you want to attend to Anna Haley at anna.haley@monash.edu.au by April 30.

Successful applicants will be notified by May 15.

ARC Centre of Excellence for Climate System Science www.climatescience.org.au

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 39

Calendar

2012 April 22–27 International Polar Year 2012: From Knowledge to Action, Montreal, Canada.

22–27 EGU General Assembly 2012, Vienna, Austria.

23–27 10th ICSHMO, Nouméa, New Caledonia.

9–13 ARC Centre of Excellence for Climate System Science’s fi rst winter school, School of Earth Sciences, Melbourne University, Melbourne.

13–25 XXXII Scientific Committee on Antarctic Research and Open Science Conference, Portland, USA. 30–3 August 16th International Conference on Cloud and Precipitation, Leipzig, Germany.

25–30 AMS 30th Conference on Hurricanes and Tropical Meteorology, Florida, USA.

30–10 August European Space Agency Earth Observation Summer School on Earth System Monitoring and Modelling, Italy.

May

August

7–11 4 World Climate Research Programme International Conference on Reanalyses, Maryland, USA.

13–17 AOGS–AGU (WPGM) Joint Assembly, Sentosa Singapore

29–1 June AMS 25th Conference on Weather Analysis and Forecasting (WAF) and the 21st Conference on Numerical Weather Predition (NWP) Jointly with the 46th Canadian Meteorological and Oceanographical Society (CMOS) Congress 2012 Montreal, Quebec, Canada.

20–24 15th Conference on Mountain Meteorology, Colorado, USA.

June

October

th

26–30 32nd International Geographic Congress, Cologne, Germany.

11–15 AGU Chapman Conference on Volcanism and the Atmosphere, Selfoss, Iceland.

22–25 NOAA’s 25th Climate Diagnostics and Prediction Workshop, Colorado, USA.

24–27 35th International Association for Energy Economics International Conference, Perth.

2013

July

February

8–13 20th Symposium on Boundary Layers and Turbulence and 18th Conference on Air-Sea Interaction, Boston, USA.

11–13 19th Annual AMOS Conference, Melbourne.

9–13 12th International Coral Reef Symposium, Cairns.

Australian Meteorological and Oceanographic Journal

Articles — Vol 61 No. 4, December 2011 Speer et al. Meteorological aspects of the 31 March 2009 Coffs Harbour flash flood.

Watterson. Calculation of joint PDFs for climate change with properties matching Australian projections.

Watterson and Whetton. An Application of Joint PDFs of climate in future decades to wheat crop yeild in Australia.

Pepler. Heat, humidity and the El Nino-Southern Oscillation in Sydney, Australia.

Klekociuk et al. The Antactic ozone hole during 2010.

Bulletin of the Australian Meteorological and Oceanographic Society Vol.25 page 40

Regular features: Imielska. Seasonal climate summary Hemisphere (Summer 2010–2011).

Southern

Wu. Quarterly Numerical Weather Prediction Model Performance Summaries — July to September 2011.

2012 AMOS Council Executive

President Vice-President Secretary Treasurer Past President

Blair Trewin Todd Lane Damien Irving Ian Watterson Neville Nicholls

Ordinary Members John Allen Andrew Klekociuk Robin Roberston Sandra Schuster Richard Wardle Perry Wiles

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AMOS Administrative Officer

Jeanette Dargaville GPO Box 1289, Melbourne VIC 3001 (attn: AMOS admin officer) Phone 0404 471 143 E-mail: admin_officer@amos.org.au

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Sub-Committee Convenors Public Relations Awards 2013 Conference Education Membership

Centre Chairs NSW Hobart Melbourne ACT Perth Darwin Brisbane Adelaide

Vacant Mark Williams Vaughan Barras Phillip Riley Michael Hewson

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Steven Phipps Kelvin Michael Damien Irving Clem Davis Merv Lynch Hakeem Shaik Hamish McGowan Andrew MacKinnon

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Representatives AMOJ Science & Technology Australia

David Karoly

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Steven Phipps

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AMOS is represented on the relevant Australian Academy of Science committees..

2012 Bulletin of the Australian Meteorological and Oceanographic Society ISSN 1035-6576

Editor

Duncan Ackerley Monash Weather and Climate School of Mathematical Sciences Monash University VIC 3800 Phone: 03-9902 4900 Fax: 03-9005 4403 Email:duncan.ackerley@monash.edu

Editor-in-chief

Stewart Allen Email: Stewart.Allen@bom.gov.au

Assistant Editors Diana Greenslade Blair Trewin Linden Ashcroft

Regional Sub-editors

Michael Hewson (Brisbane) Caecilia Ewenz (Adelaide) Nicholas Tyrrell and Luke Hande (Melbourne) Fiona Johnson (NSW) Clem Davis (ACT)

Contributors Blair Trewin Gary Brassington Paul Sandery Andy Taylor

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Publisher

AMOS, GPO Box 1289, Melbourne VIC 3001, Australia

Contributed articles, news, announcements and correspondence for the Bulletin should be sent to the editor no later than 18 May 2012. They will be reviewed and the galley proofs returned to the author if requested. An ASCII version of the text is required via e-mail or digital media to minimise typographic errors.

The Bulletin of the Australian Meteorological and Oceanographic Society is produced and distributed with the assistance of CSIRO Marine and Atmospheric Research and the Bureau of Meteorology.

AMOS Website: www.amos.org.au